I woke at 3 this morning with a simple answer: one technical bit of prep hadn't happened. I didn't want to wake anybody up getting up to fix it, so I made a mental note to deal with it first thing on getting up and went back to sleep. Hurray for sleeping on a problem!
I didn't get back to sleep at once--and ten minutes later realized that it would have never worked in the first place without the prep. That hadn't been the answer.
Middle-of-the-night realizations have never been correct for me. Nor have midnight plot ideas worked.
Some people's dreams are useful. Not mine.